Vacuum muffler



E G GUNN VACUUM MUFFLER Filed Sept. 1, 1955 July 14, 1936.

Patented July 14, 1936 v UNITED STATES PATENT- OFFICE 2,041,715 VACUUM MUFFLER Earl G. :Gunn, Racine, Wis., assignor to Walker Manufacturing 00., Racine, Win, a corporation of Wisconsin My invention relates to an improved mufller such as used for the silencing of exhaust gas noises of internal combustion engines, in which the flow of gases through the mufiler is utilized for the production or creation of a vacuum for serving other devices requiring a vacuum-operating medium,

One of the objects 01' my invention is to provide a mullier structure for silencing exhaust gas noises, and means in association .therewith by which the gas flow through the muiiler is caused to generate a vacuum which is made available for other operating purposes.

A further object is to provide meansfor automatically maintaining a vacuum within a suitable range for operating requirements, irrespective of the pressure variations oi the exhaust gases passed through the mutter. g

Other objects of the invention will appear from the following description and the accompanying drawing, which illustrate one embodiment of the invention. D

In the drawing,

Fig. 1 is a central longitudinal sectional view of a structure embodying the invention;

Fig. 2 is an enlarged transverse section on. the line 2-4.? of Fig. 1;

Fig. 3 is an enlarged transverse section on the line 3-3 oi Fig. 1; and

Fig. 4 is an enlarged detail section of the automatic valve and associated parts.

The murder shown in the drawing embodies an elongated cylindrical shell A which houses the operating parts and which is of a diameter and length adapted to the available space on an automobile for the accommodation of a mufiier. The shell is closed atits ends by flanged dish-shaped heads l and 2 which are secured to the ends oi the cylinder wall by welding or otherwise. A flanged transverse partition wall 3 is secured in the shell at a distance from the head i and .closes off a portion of the shell to provide a chamber B.

The head i has a central opening 4 and a tubular extension 5 forming the inlet and adapted for connection to the exhaust pipe of the engine or other source of-gas. The partition 3 likewise has" a central flanged opening 6.

A straight through tube 7!, of considerably less diameter than the shell, extends centrally through chamber B and connects at its ends with tition wall In is secured in the shell and closes off the other endportion thereof to provide a closed chamber C, and a centrally disposed tubular member ll extends longitudinally through this chamber from partition In to the closure head 2 5 of the shell. The closure head has a central opening l2 and'a tubular extension I3 forming the outlet or exhaust end of the muffler. The

opening it in partition it is smaller in diameter and the flange it surrounding said opening is 10 tapered to still smaller diameter. A portion it of the tube ii is tapered down to the diameter of the flange opening and then flared in the flange l5, thus providing a throat opening ll somewhat less in diameter than the main portion of tube 15 ii. The tubes ll and i l and the several openings in the shell heads and partitions are all axially aligned.

The partitions ti and it are spaced apart sunlciently to provide short chamber D in the shell, 20 which chamber is in communication with both tubes l and it through openings 6 and it, but is not in communication with either of the sham hers B and C. This chamber D is provided for the accommodation of an automatic pressure responsive valve which controls the flow of gas through tube 7 into tube it, and which will be hereinafter described.

The tube l and the tube [1 i, with the exception of its tapered portion l t, are provided with a large 39 number of small louvered openings i8 distributed relative to the tubes, and the openings form the 35 only communication between the tube passages and the chambers B and G through which the tubes extend.

It is by means of the structure described that the muifiing or sound destroying functions are performed. The gas stream enters the inlet end of tube l in a rapid series of sharp pulsations and the pressure and sound waves resulting'there from expand into the closed chambers B and C through the openings it as the gas stream flows through the tubes. The gases entering the chamhers are given a circumferential direction oi. movement in said chambers, and since they cannot escape from the chambers they re-enter the 56 iorm or steady pressure, with the result that the 55 gases leavingthe discharge outlet oi the structure emit no appreciable audible sound.

Within. the tube '3 is provided a means for utilizing the stream of gases through the mumer for creating a vacuum which can be utilized for operating other devices such as horns and wind shield wipers. This means in the present structure comprises a Venturi tube disposed concentri= cally within the gas passage tube '6. they be of any suitable construction for the purpose. in the structure shown, the Venturi tube is. made or a short, sharply tapered section 2% and a. long tapered section 2 i placed end to end to form the throct of the venturi. 'lhese ends have openings of the same diameter but they are spaced apart slightly to provide a port or e-nnuler opening 22 which communicates with a smell chamber 23 formed. by an enclosure 2 which surrounds the end portions of the Venturi tube sections and which has no communication whatever with the tube 7 or chamber B for the reason that the vacuum is created in the chamber 28. Chamber 253 is connected by e. stem 25 to suitable fitting 26 on. the exterior of shell A, so that suitable connecticn for the vacuum can be made with the devices to be operated thereby.

The Venturi section it speces the interior of tube l and is secured to the wall thereoi for support, but ithas an annular series of ope-lugs 2i through which the gases can flow into the portion of the tube beyond the member 2b. In operation the gas stream entering the inlet end oi tube l divides, partly through the Venturi tube and partly through the openings 2? and the remaining portion of tube if, so that in'a sense the passage in tube ll may be referred to as a by-pass around the venturi. That portion, therefore, of the gases which flow through the venturi creates a vacuum in chamber 23 and the rest oi the geses by-pass around the venturi.

The pressure and velocity of the incog varies greatly with the speed of the engine from which the gases emanate, and this variation in pressure and velocity correspondingly efiects the degree of vacuum produced. .Fior instance, h the engine is idling, the pressure and velocity of the exhaust gases are so low that the velocity of the portion of the gases going through the Venturi tube is insuflicient to develop a degree oi vecu sufllclent for the operation of the devices connected therewith, whereas under running conditions of the engine the pressure and velocity of the gases are sumcient for the production of a phragm 3|, of course, acts as a flexible partition.

and to prevent the passage 01' gases through said chamber D other than that which is permittedby the position of the ring or valve member 301 Normally the ring valve is held by the tension in the diaphragm close to the tube so'that the passage of gas ispractically prevented. Now, it the enzinc is idling and the incoming gases are low in 1 pressure and velocity, the ring valve prevents the by-passlng 01 any of the gases through openings and tube I, and practically all of the gas stream passes through the venturi. This is suflicient to produce a low enough vacuum for operative purposes. However, as the engine is speeded up and greater pressure and velocity is developed in the gases, a suficient now will occur through the 5 venturi and the excess gases will pass through openings 21 and through tube l around the venturl. Under these conditions the pressure will act on the diaphragm to force the ring away from tube 29 and permit the gases to flow through the opening. At the same time there will be no appreciable back pressure developed in the mumer under any speed conditions oi the engine.

if claim:

1. In a inuiller oi the character described, the 15 combination oi a shell having a tubular member therein for the passage of the exhaust gas stream, means within said tubular member responsive to the how oi the gm streem. through said tubular member for producing a vacuum, and a pressure 20 actuated device responsive to excess gas pressure in said tubular member for permitting the flow of gas through said tubular member independeutly of said vacuum producing means. 7

2. in a structure of character described, the 25- combination of a muifier inclug an outer shell for silencing the sound of exhaust gases and hov ing a pair of tubular members within and spaced from said shell and forming concentric passages for the flow of gas therethrough, means essociated with. the inner or said tubes for producing a vacuum by virtue of the flow of gas there through, a device adjacent the end of saidlnner tube for controlling the ilow of gases through the outer one of said passages, and means responsive 35 to the pressure of gas in said outer passage for actuating said device.

3. In a structure of the character described, the combination of a muiiier including means for silencing the sound oi exhaust gases and having a pair of tubular members forming concentric passages for the flow of gas therethrough, the

inner oi said tubes including a Venturi tube for producing a vacuum by the flow of the gmes therethrough, a transverse diaphragm in said muffler adjacent the ends of said tubes responsive to the pressure of the gas flowing in the outer of said tubes, and a member carried by said diaplnugm'for controlling the flow of gases through the outer of said tubes.

4. In a structure of the character described, the combination cl 2. mumer having means including a tubular member for silencing the sound of exhaust gases, a Venturi tube in said tubular member for producing a vacuum in response to theflowof gas through said Venturi tube, said tubular member surrounding said Venturi tube and terminating adjacent the end thereof and her-extending lengthwise of said shell and-forming a passage for the gases, 9, Venturi tube vacuum producing device positioned within said tubular memberto receive part of the flow of the gases through said tubular member and, a flexible transverse diaphragm partition in said shell having means adjacent the end of the Venturi tube for substantially preventing the flow of gas through the tubular member around the Venturi 1| tube until, the gas pressure exceeds that required to cause a sufllcient flow of gas through said Venturi tube vacuum means.

6. In a structure of the character, described, the combination of a murder including a cylindrical shell and a straight through tubular member extending lengthwise of said shell and forming a passage for the gases, a Venturi tube vacuum producing device positioned within said tubular member to receive part of the flow of the gases through said tubular member, a flexible transverse diaphragm partition in said shell having means adjacent the end of the Venturi tube for substantially preventing the flow oi! gas through the tubular member around the Venturi tube until, the gas pressure exceeds that required to cause a sufficient flow of gas through said Venturi tube vacuum means, and a second tubular member in said shell axially aligned with the first tubular member and the Venturi tube to receive the flow of gases through both the Venturi tube and the flrst tubular member.

7. In a structure of the character described, the combination 01' a cylindrical shell closed at its ends, transverse intermediate partitions spaced apart to divide the interior of said shell into an intermediate chamber and end chambers, a straight tubular member extending from the end of the shell through one end chamber and communicating with said intermediate chamber, a second tubular member communicating with said intermediate chamber at its inner end and extending through the other end chamber, a Venturi tube positioned within said first tubular member and through which a portion of the gases flow for the purpose of producing a vacuum, the end of said Venturi tube extending into said intermediate chamber, and a flexible diaphragm in said intermediate chamber adjacent the end of said Venturi tube for preventing the flow of gas through said straight tubular member around the Venturi tube until the pressure of gas reaches a predetermined degree.

8. In a structure of the character described, the combination of a muilier including a'tubular member, and a shell surrounding said tubular member providing an annular sound silencing chamber, said tubular member forming a tubular passage for the flow of gases, pressure responsive means operable to open said passage when the gases therein reach a predetermined pressure, and a vacuum producing device in said tubular passage responsive to the flow of the gases in said tubular member.

9. In a structure of the character described,

to the pressure of the gases therein, and means,

including an outer shell surrounding said tubular member, for silencing the sound of the gases flowing through said tubular member.

10. In a muflier of the class described, the combination of an outer shell and an inner'tubular member arranged to silence the sound of ,gases flowing through said inner tubular member, said 20 inner tubular member having one end terminating within said shell, a vacuum producing Nenturi tube positioned within said inner tubular member and having its discharge end positioned adjacent the end of said inner tubular member and spaced from said inner'tubuiar member to form a passage for the flow of gases, and pressure responsive means at the end of said Venturi tube for controlling the flow oi. gases from said passage whereby the flow of gases from said passage adjacent the end of the Venturi tube will create suction in said Venturi tube to assist the flow of gases therethroughfeg 11. In a structureof the class described, the combination of a tubular member and a Venturi tube positioned within said tubular member and spaced from the wall thereof to form an annular passage for the gases surrounding said Venturi tube, a member for controlling the flow of gases EARL a; GUNN. 

